Yeah, I know about that option. But I have too many books on my tablet and it takes forever to scan them all, sometimes the app even freezes.

However, I discovered that if I place a copy of a book I want to import in "Downloads" folder, it gets scanned before all the other books that are in "Ebooks" folder. After that I can stop the search and import only that particular book.

It's a satisfying work-around for not having an option to manually choose which books to import prior the actual search.